/// <summary>
/// This is a name-based indexer into the Zip archive.
/// </summary>
///
/// <remarks>
/// <para>
/// This property is read-only.
/// </para>
///
/// <para>
/// The <see cref="CaseSensitiveRetrieval"/> property on the <c>ZipFile</c>
/// determines whether retrieval via this indexer is done via case-sensitive
/// comparisons. By default, retrieval is not case sensitive. This makes
/// sense on Windows, in which filesystems are not case sensitive.
/// </para>
///
/// <para>
/// Regardless of case-sensitivity, it is not always the case that
/// <c>this[value].FileName == value</c>. In other words, the <c>FileName</c>
/// property of the <c>ZipEntry</c> retrieved with this indexer, may or may
/// not be equal to the index value.
/// </para>
///
/// <para>
/// This is because DotNetZip performs a normalization of filenames passed to
/// this indexer, before attempting to retrieve the item. That normalization
/// includes: removal of a volume letter and colon, swapping backward slashes
/// for forward slashes. So, <c>zip["dir1\\entry1.txt"].FileName ==
/// "dir1/entry.txt"</c>.
/// </para>
///
/// <para>
/// Directory entries in the zip file may be retrieved via this indexer only
/// with names that have a trailing slash. DotNetZip automatically appends a
/// trailing slash to the names of any directory entries added to a zip.
/// </para>
///
/// </remarks>
///
/// <example>
/// This example extracts only the entries in a zip file that are .txt files.
/// <code>
/// using (ZipFile zip = ZipFile.Read("PackedDocuments.zip"))
/// {
/// foreach (string s1 in zip.EntryFilenames)
/// {
/// if (s1.EndsWith(".txt"))
/// zip[s1].Extract("textfiles");
/// }
/// }
/// </code>
/// <code lang="VB">
/// Using zip As ZipFile = ZipFile.Read("PackedDocuments.zip")
/// Dim s1 As String
/// For Each s1 In zip.EntryFilenames
/// If s1.EndsWith(".txt") Then
/// zip(s1).Extract("textfiles")
/// End If
/// Next
/// End Using
/// </code>
/// </example>
///
/// <exception cref="System.ArgumentException">
/// Thrown if the caller attempts to assign a non-null value to the indexer.
/// </exception>
///
/// <param name="fileName">
/// The name of the file, including any directory path, to retrieve from the
/// zip. The filename match is not case-sensitive by default; you can use the
/// <see cref="CaseSensitiveRetrieval"/> property to change this behavior. The
/// pathname can use forward-slashes or backward slashes.
/// </param>
///
/// <returns>
/// The <c>ZipEntry</c> within the Zip archive, given by the specified
/// filename. If the named entry does not exist in the archive, this indexer
/// returns <c>null</c> (<c>Nothing</c> in VB).
/// </returns>
///
public ZipEntry this[String fileName]
{
get
{
var key = SharedUtilities.NormalizePathForUseInZipFile(fileName);
if (_entries.ContainsKey(key))
return _entries[key];
// workitem 11056
key = key.Replace("/", "\\");
if (_entries.ContainsKey(key))
return _entries[key];
return null;
}
}
/// <summary>
/// Returns true if an entry by the given name exists in the ZipFile.
/// </summary>
///
/// <param name='name'>the name of the entry to find</param>
/// <returns>true if an entry with the given name exists; otherwise false.
/// </returns>
public bool ContainsEntry(string name)
{
// workitem 12534
return _entries.ContainsKey(SharedUtilities.NormalizePathForUseInZipFile(name));
}